Commit 1a892b48 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs updates from Miklos Szeredi:
 "This update contains fixes to the "use mounter's permission to access
  underlying layers" area, and miscellaneous other fixes and cleanups.

  No new features this time"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: use vfs_get_link()
  vfs: add vfs_get_link() helper
  ovl: use generic_readlink
  ovl: explain error values when removing acl from workdir
  ovl: Fix info leak in ovl_lookup_temp()
  ovl: during copy up, switch to mounter's creds early
  ovl: lookup: do getxattr with mounter's permission
  ovl: copy_up_xattr(): use strnlen
parents 5d89d9f5 7764235b

fs/namei.c

+25 −0
Original line number Diff line number Diff line
@@ -4668,6 +4668,31 @@ int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 
}

EXPORT_SYMBOL(generic_readlink);



/**

 * vfs_get_link - get symlink body

 * @dentry: dentry on which to get symbolic link

 * @done: caller needs to free returned data with this

 *

 * Calls security hook and i_op->get_link() on the supplied inode.

 *

 * It does not touch atime.  That's up to the caller if necessary.

 *

 * Does not work on "special" symlinks like /proc/$$/fd/N

 */

const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)

{

	const char *res = ERR_PTR(-EINVAL);

	struct inode *inode = d_inode(dentry);



	if (d_is_symlink(dentry)) {

		res = ERR_PTR(security_inode_readlink(dentry));

		if (!res)

			res = inode->i_op->get_link(dentry, inode, done);

	}

	return res;

}

EXPORT_SYMBOL(vfs_get_link);



/* get the link contents into pagecache */

const char *page_get_link(struct dentry *dentry, struct inode *inode,

			  struct delayed_call *callback)

fs/overlayfs/copy_up.c

+20 −47
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) 
	ssize_t list_size, size, value_size = 0;

	char *buf, *name, *value = NULL;

	int uninitialized_var(error);

	size_t slen;



	if (!(old->d_inode->i_opflags & IOP_XATTR) ||

	    !(new->d_inode->i_opflags & IOP_XATTR))
@@ -79,7 +80,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) 
		goto out;

	}



	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {

	for (name = buf; list_size; name += slen) {

		slen = strnlen(name, list_size) + 1;



		/* underlying fs providing us with an broken xattr list? */

		if (WARN_ON(slen > list_size)) {

			error = -EIO;

			break;

		}

		list_size -= slen;



		if (ovl_is_private_xattr(name))

			continue;

retry:
@@ -174,40 +184,6 @@ out_fput: 
	return error;

}



static char *ovl_read_symlink(struct dentry *realdentry)

{

	int res;

	char *buf;

	struct inode *inode = realdentry->d_inode;

	mm_segment_t old_fs;



	res = -EINVAL;

	if (!inode->i_op->readlink)

		goto err;



	res = -ENOMEM;

	buf = (char *) __get_free_page(GFP_KERNEL);

	if (!buf)

		goto err;



	old_fs = get_fs();

	set_fs(get_ds());

	/* The cast to a user pointer is valid due to the set_fs() */

	res = inode->i_op->readlink(realdentry,

				    (char __user *)buf, PAGE_SIZE - 1);

	set_fs(old_fs);

	if (res < 0) {

		free_page((unsigned long) buf);

		goto err;

	}

	buf[res] = '\0';



	return buf;



err:

	return ERR_PTR(res);

}



static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)

{

	struct iattr attr = {
@@ -354,19 +330,20 @@ out_cleanup: 
int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,

		    struct path *lowerpath, struct kstat *stat)

{

	DEFINE_DELAYED_CALL(done);

	struct dentry *workdir = ovl_workdir(dentry);

	int err;

	struct kstat pstat;

	struct path parentpath;

	struct dentry *lowerdentry = lowerpath->dentry;

	struct dentry *upperdir;

	struct dentry *upperdentry;

	const struct cred *old_cred;

	char *link = NULL;

	const char *link = NULL;



	if (WARN_ON(!workdir))

		return -EROFS;



	ovl_do_check_copy_up(lowerpath->dentry);

	ovl_do_check_copy_up(lowerdentry);



	ovl_path_upper(parent, &parentpath);

	upperdir = parentpath.dentry;
@@ -376,13 +353,11 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
		return err;



	if (S_ISLNK(stat->mode)) {

		link = ovl_read_symlink(lowerpath->dentry);

		link = vfs_get_link(lowerdentry, &done);

		if (IS_ERR(link))

			return PTR_ERR(link);

	}



	old_cred = ovl_override_creds(dentry->d_sb);



	err = -EIO;

	if (lock_rename(workdir, upperdir) != NULL) {

		pr_err("overlayfs: failed to lock workdir+upperdir\n");
@@ -403,19 +378,16 @@ int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	}

out_unlock:

	unlock_rename(workdir, upperdir);

	revert_creds(old_cred);



	if (link)

		free_page((unsigned long) link);

	do_delayed_call(&done);



	return err;

}



int ovl_copy_up(struct dentry *dentry)

{

	int err;

	int err = 0;

	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);



	err = 0;

	while (!err) {

		struct dentry *next;

		struct dentry *parent;
@@ -447,6 +419,7 @@ int ovl_copy_up(struct dentry *dentry) 
		dput(parent);

		dput(next);

	}

	revert_creds(old_cred);



	return err;

}

fs/overlayfs/dir.c

+4 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/cred.h>

#include <linux/posix_acl.h>

#include <linux/posix_acl_xattr.h>

#include <linux/atomic.h>

#include "overlayfs.h"



void ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
@@ -37,8 +38,10 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir, struct dentry *dentry) 
{

	struct dentry *temp;

	char name[20];

	static atomic_t temp_id = ATOMIC_INIT(0);



	snprintf(name, sizeof(name), "#%lx", (unsigned long) dentry);

	/* counter is allowed to wrap, since temp dentries are ephemeral */

	snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));



	temp = lookup_one_len(name, workdir, strlen(name));

	if (!IS_ERR(temp) && temp->d_inode) {

fs/overlayfs/inode.c

+10 −34
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ static int ovl_copy_up_truncate(struct dentry *dentry) 
	struct dentry *parent;

	struct kstat stat;

	struct path lowerpath;

	const struct cred *old_cred;



	parent = dget_parent(dentry);

	err = ovl_copy_up(parent);
@@ -26,12 +27,14 @@ static int ovl_copy_up_truncate(struct dentry *dentry) 
		goto out_dput_parent;



	ovl_path_lower(dentry, &lowerpath);

	err = vfs_getattr(&lowerpath, &stat);

	if (err)

		goto out_dput_parent;



	old_cred = ovl_override_creds(dentry->d_sb);

	err = vfs_getattr(&lowerpath, &stat);

	if (!err) {

		stat.size = 0;

		err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);

	}

	revert_creds(old_cred);



out_dput_parent:

	dput(parent);
@@ -153,45 +156,18 @@ static const char *ovl_get_link(struct dentry *dentry, 
				struct inode *inode,

				struct delayed_call *done)

{

	struct dentry *realdentry;

	struct inode *realinode;

	const struct cred *old_cred;

	const char *p;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	realdentry = ovl_dentry_real(dentry);

	realinode = realdentry->d_inode;



	if (WARN_ON(!realinode->i_op->get_link))

		return ERR_PTR(-EPERM);



	old_cred = ovl_override_creds(dentry->d_sb);

	p = realinode->i_op->get_link(realdentry, realinode, done);

	p = vfs_get_link(ovl_dentry_real(dentry), done);

	revert_creds(old_cred);

	return p;

}



static int ovl_readlink(struct dentry *dentry, char __user *buf, int bufsiz)

{

	struct path realpath;

	struct inode *realinode;

	const struct cred *old_cred;

	int err;



	ovl_path_real(dentry, &realpath);

	realinode = realpath.dentry->d_inode;



	if (!realinode->i_op->readlink)

		return -EINVAL;



	old_cred = ovl_override_creds(dentry->d_sb);

	err = realinode->i_op->readlink(realpath.dentry, buf, bufsiz);

	revert_creds(old_cred);

	return err;

}



bool ovl_is_private_xattr(const char *name)

{

	return strncmp(name, OVL_XATTR_PREFIX,
@@ -375,7 +351,7 @@ static const struct inode_operations ovl_file_inode_operations = { 
static const struct inode_operations ovl_symlink_inode_operations = {

	.setattr	= ovl_setattr,

	.get_link	= ovl_get_link,

	.readlink	= ovl_readlink,

	.readlink	= generic_readlink,

	.getattr	= ovl_getattr,

	.listxattr	= ovl_listxattr,

	.update_time	= ovl_update_time,

fs/overlayfs/super.c

+22 −11
Original line number Diff line number Diff line
@@ -273,12 +273,11 @@ static bool ovl_is_opaquedir(struct dentry *dentry) 
{

	int res;

	char val;

	struct inode *inode = dentry->d_inode;



	if (!S_ISDIR(inode->i_mode) || !(inode->i_opflags & IOP_XATTR))

	if (!d_is_dir(dentry))

		return false;



	res = __vfs_getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1);

	res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);

	if (res == 1 && val == 'y')

		return true;
@@ -419,16 +418,12 @@ static bool ovl_dentry_weird(struct dentry *dentry) 
				  DCACHE_OP_COMPARE);

}



static inline struct dentry *ovl_lookup_real(struct super_block *ovl_sb,

					     struct dentry *dir,

static inline struct dentry *ovl_lookup_real(struct dentry *dir,

					     const struct qstr *name)

{

	const struct cred *old_cred;

	struct dentry *dentry;



	old_cred = ovl_override_creds(ovl_sb);

	dentry = lookup_one_len_unlocked(name->name, dir, name->len);

	revert_creds(old_cred);



	if (IS_ERR(dentry)) {

		if (PTR_ERR(dentry) == -ENOENT)
@@ -469,6 +464,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			  unsigned int flags)

{

	struct ovl_entry *oe;

	const struct cred *old_cred;

	struct ovl_entry *poe = dentry->d_parent->d_fsdata;

	struct path *stack = NULL;

	struct dentry *upperdir, *upperdentry = NULL;
@@ -479,9 +475,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
	unsigned int i;

	int err;



	old_cred = ovl_override_creds(dentry->d_sb);

	upperdir = ovl_upperdentry_dereference(poe);

	if (upperdir) {

		this = ovl_lookup_real(dentry->d_sb, upperdir, &dentry->d_name);

		this = ovl_lookup_real(upperdir, &dentry->d_name);

		err = PTR_ERR(this);

		if (IS_ERR(this))

			goto out;
@@ -514,8 +511,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
		bool opaque = false;

		struct path lowerpath = poe->lowerstack[i];



		this = ovl_lookup_real(dentry->d_sb,

				       lowerpath.dentry, &dentry->d_name);

		this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);

		err = PTR_ERR(this);

		if (IS_ERR(this)) {

			/*
@@ -588,6 +584,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
		ovl_copyattr(realdentry->d_inode, inode);

	}



	revert_creds(old_cred);

	oe->opaque = upperopaque;

	oe->__upperdentry = upperdentry;

	memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
@@ -606,6 +603,7 @@ out_put: 
out_put_upper:

	dput(upperdentry);

out:

	revert_creds(old_cred);

	return ERR_PTR(err);

}
@@ -834,6 +832,19 @@ retry: 
		if (err)

			goto out_dput;



		/*

		 * Try to remove POSIX ACL xattrs from workdir.  We are good if:

		 *

		 * a) success (there was a POSIX ACL xattr and was removed)

		 * b) -ENODATA (there was no POSIX ACL xattr)

		 * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)

		 *

		 * There are various other error values that could effectively

		 * mean that the xattr doesn't exist (e.g. -ERANGE is returned

		 * if the xattr name is too long), but the set of filesystems

		 * allowed as upper are limited to "normal" ones, where checking

		 * for the above two errors is sufficient.

		 */

		err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);

		if (err && err != -ENODATA && err != -EOPNOTSUPP)

			goto out_dput;

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